1. Field of the Invention
The invention relates to a transport and storage container for liquids, comprising: a pallet-shaped support frame of electrically conducting metal or of an electrically conducting plastic material; an exchangeable single-layer or multi-layer inner container of plastic material positioned on the support frame and having an electrically conducting outer layer for electrically grounding the outer surface of the container, wherein the inner container is configured as a parallelepipedal or cubic container having four sidewalls, a bottom and a top wall, a closable filling socket at the top wall, and an outlet socket that is arranged in one of the sidewalls in the area of the bottom and is designed to receive a tap fixture; and an outer jacket that surrounds the inner container and is made of metallic bars forming a wire mesh or of sheet metal.
2. Description of the Related Art
A transport and storage container for liquids of this kind is disclosed in German patent application DE 101 24 681 A1. It is provided with electric grounding of the inner plastic container, wherein the electric grounding comprises an electrically conducting area that extends as a unitary part from the inner side to the outer side of the inner container. The inner plastic container has an electrically conducting external layer that serves, together with the outer jacket comprised of metallic bars forming a mesh or sheet metal and the metallic support frame, as an outer electric grounding in order to prevent electrostatic charging of the surface of the inner plastic container caused by friction during transport and handling of the container.
For electrically grounding the interior (filling space) of the inner plastic container, the tap fixture of the container is used that is embodied as a slide valve and is fastened by means of a spigot nut on the outlet socket of the inner container; its inlet projects into the interior. The slide valve housing has an inner paint coat and an outer paint coat comprising electrically conducting polymers. Electric charges that occur by liquid friction on the inner surface of the container and within the liquid itself during filling and emptying of the inner container and during stirring of liquid within the inner container, for example, for mixing purposes, are dissipated via the slide valve housing, the spigot nut that is manufactured of electrically conducting material, the external layer of the inner container, the outer jacket of the transport and storage container, and the pallet-shaped support frame.
The permanent antistatic configuration of the tap fixture of the inner container that is required for the inner electric grounding of the inner container of the transport and storage container causes the manufacturing costs of the container to become more expensive.
German patent application DE 197 31 518 A1 discloses a transport and storage container for liquids that is electrically grounded by a mesh cover that is placed onto the inner plastic container or an electrically conducting net or mesh applied to the inner container. As a result of this external grounding, only those electrical charges present on the container surface are dissipated. Moreover, the electrical grounding of the liquid container by means of a mesh cover, a net or a mesh is technically complex and results in a corresponding increase of the manufacturing costs.
In a transport and storage container for liquids disclosed in German patent application DE 198 15 082 A1, the tap fixture connected to the outlet socket of the inner container is provided with a grounding element that is formed as a curved sheet metal or plate made of metal that extends across a partial area of the inner bore of the tap fixture and is connected by means of a fastening screw and a ground wire to the support frame of the container. By means of the internal grounding only the electrical charges that are produced by liquid friction within the liquid are dissipated. Moreover, in this liquid container there is the risk that during transport and storage of aggressive liquids the grounding element will become damaged by liquid to such an extent that the electrical grounding action is no longer functional.